This is the first in a series of changes to the OpenMP runtime that have been done internally by Microsoft. This patch makes the necessary changes to enable libomp.dll to build with the MSVC compiler targeting ARM64.
Exciting! Thank you.
If I understand correctly, we presently have neither windows nor aarch64 working. Doing both of those at the same time sounds hazardous. Mixes a variety of failure modes.
We could enable windows on x86-64, which will hammer out things like uses of dlopen. That can probably be tested via a virtual machine running on a linux host, or maybe on Azure.
We could enable linux on aarch64, which may be almost a no-op. That can probably be tested via qemu for people who don't have an aarch64 box, or maybe on AWS.
If we can get linux/aarch64 passing tests, and windows/x64 passing tests, there's a much reduced cross section for bugs when trying windows/aarch64.
edit: there's also the host compiler split, building this with clang / msvc / other, which probably induces a different axis of bugs
We talked about this in our OpenMP in LLVM meeting (https://docs.google.com/document/d/1Tz8WFN13n7yJ-SCE0Qjqf9LmjGUw0dWO9Ts1ss4YOdg/edit?usp=sharing) today and we are looking for people and ways to test and review this.
It might be good if you could join us next Wednesday and give a short talk about the overall plan, what patches we can expect, buildbots, things like that.
I'm confused about this statement. Does this mean that libomp is not available for Windows at all, for any architecture? I'm confused because I see libomp.dll as a part of the pre-built Windows binaries that users can download, for at least for x64 which I have installed.
That was my understanding, but not surprised to be wrong. I'm almost certain libomptarget doesn't work on windows. Libomp.dll suggests that part does build for windows, so given that information I'd then assume it passes tests too.
This patch does however read like two orthogonal sets of fixes, some for windows (which might mean msvc? Code says windows, description says msvc), some for aarch64.
I think this applies to the libomptarget library.
libomp work on Windows, I used it successfully myself. When Intel donated the library, Windows was supported from the beginning. The only problem I had is that the clang driver incorrectly wants to link to libomp.lib, but only a libomp.dll.lib is built. I don't know the status of AARCH64 though.